Anki is fantastic

According to me I think that the best way to remember a word is by making that word active in your sentences.Make the use of the word you recently got to know let it come into play each an everytime you speak or think of forming a sentence that to more precisely!

I find that the best way is to find a way to associate a word with an image you create in your mind. The more unusual the image the better. For ex.  bercer is a French word meaning to rock or cradle a baby, also to sooth or to lull someone into believe lies. My image is a bear rocking a cradle with a plate on his head. There are some words I have struggled to remember for weeks, till I did this and almost immediately I will remember. You can also do the same thing drawing pictures but that takes too long for me.

Learning with pictures

Another vote for Anki https://apps.ankiweb.net/